Bioluminescence in certain organisms via the reaction of luciferin and luciferase is well known in the art. The use of the luciferase enzyme has become highly valuable as a genetic marker gene due to the convenience, sensitivity and linear range of the luminescence assay. Luciferase has been used in many experimental biological systems in both prokaryotic and eukaryotic cell culture, transgenic plants and animals, as well as cell-free expression systems.
For example, Japanese Firefly Luciola cruciata luciferase expression can be monitored as a genetic marker in cell extracts when mixed with substrates (D-luciferin, Mg2+ ATP, and O2), and the resulting luminescence measured using a luminescent detection device (containing a photomultiplier system or equivalent) such as liminometers or scintillation counters without the need of a reagent injection device. The Luciola cruciata luciferase activity can also be detected in living cells by adding D-luciferin or more membrane permeant analogs such as D-luciferin ethyl ester to the growth medium. This in vivo luminescence relies on the ability of D-luciferin or more membrane permeant analogs to diffuse through cellular and intracellular organelle membranes and on the intracellular availability of ATP and O2 in these cells.
Despite its utility as a reporter, current luciferases isolated from various organisms, including insects and marine organisms are not necessarily optimized for expression or production in systems that are of most interest to the medical community and experimental molecular biologists. Accordingly, a need exists for a luciferase nucleic acid molecule that allows improved protein production in mammalian cells and tissues.